1. Field of the Invention
The present invention relates to an image forming apparatus, a sheet feed control method, and a storage medium storing a non-transitory computer-readable storage medium storing a computer-executable program for causing a computer to execute the sheet feed control method.
2. Description of the Related Art
In general, some image forming apparatus is provided with a plurality of sheet feeders (e.g. sheet feeding cassettes), for selectively feeding recording sheets (hereinafter also simply referred to as “sheets”) from the sheet feeding cassettes. Further, some image forming apparatus is equipped with a so-called manual feed tray, which is another sheet feeder different from the sheet feeding cassettes.
Conventionally, when an image is to be printed on a non-standard size sheet using a color image forming apparatus, a user sets the manual feed tray to a user-defined size for the size of sheets, and causes the color image forming apparatus to perform printing. The term “user-defined size” is intended to mean a non-standard size in which the vertical and lateral lengths of a recording sheet are designated by the user.
In such a color image forming apparatus, when a request for printing an image having a non-standard size is received, a recording sheet is fed from the manual feed tray having the user-defined size set thereto, for printing the image. When the recording sheet is fed with the size of the recording sheet being unknown, if the size of the image is larger than the size of the sheet, an excess amount of a recording material (toner) beyond the range of the size of the sheet is scattered in the image forming apparatus. If the recording material is scattered in the image forming apparatus, the quality of an image formed thereafter is sometimes adversely affected by the scattered recording material. To eliminate this inconvenience, in the conventional color image forming apparatus, the scattering of the recording material is prevented by causing the user to designate the size of the sheet.
On the other hand, when an image is to be printed on a non-standard size sheet using a monochrome image forming apparatus, a user sets the sheet size of the manual feed tray to a so-called free size and causes the monochrome image forming apparatus to perform printing. The term “free size” is intended to mean a non-standard size in which the user does not designate the vertical and lateral lengths of a recording sheet. If the free size is used, it is not necessary for the user to set the size of a recording sheet used for the printing, thereby making it possible to save user's time and labor for setting the size of the sheet. Although the color image forming apparatus uses four color recording materials to form an image, the monochrome image forming apparatus uses only one color recording material to form an image. Therefore, in the monochrome image forming apparatus, it is possible to reduce the amount of scattered toner even when a sheet is fed from a sheet feeder set to the free size, and hence the monochrome image forming apparatus is configured to permit the free size to be set. In such a monochrome image forming apparatus, when a request for printing an image having a non-standard size is received, the image is printed by feeding a recording sheet from the manual feed tray set to the free size.
Further, as a conventional technique, there has been proposed a technique in which designation of the free size is permitted when performing monochrome printing having less possibility of scattering of toner, whereas when performing color printing, the user is required to designate a user-defined size (see e.g. Japanese Patent Laid-Open Publication No. 2004-4622).
In the conventional image forming apparatus, however, it is impossible to set in advance a plurality of accommodating units, such as the sheet feeding cassettes and the manual feed tray, to respective non-standard sizes different from each other. For example, it is impossible to set in advance the sheet feeding cassettes to user-defined sizes while setting the manual feed tray to a free size.
Therefore, when a request for printing a non-standard size image is received, the conventional image forming apparatus suffers from the following problems:
In a case where the manual feed tray has been set to a user-defined size, if the vertical length and the lateral length of the user-defined size do not match those of sheets set in the manual feed tray, printing is stopped due to a sheet feeding error.
Further, in a case where the manual feed tray has been set to a free size, the image is sometimes not printed on a recording sheet of a size desired by the user since the size of the image requested to be printed does not necessarily match the size of recording sheets set in the manual feed tray.